Automatically generated high-performance code for discrete wavelet transforms

A growing number of performance-critical DSP applications use the discrete wavelet transform (DWT), thus prompting the need for highly efficient DWT software implementations. Unfortunately, the rapid evolution of computing platforms and compiler technology makes carefully hand-tuned code obsolete almost as fast as it is written. In this paper, we describe our work on the automatic generation of DWT implementations that are tuned to a given platform. Our approach captures the various DWT algorithms in a concise mathematical framework that enables the integration of DWTs into the SPIRAL code generation system. Experiments show the quality of our automatically generated code and provide interesting insights; for example, the fastest code differs between platforms and is usually based on a non-obvious combination of DWT algorithms.